Validate UML Model and OCL Expressions Using USE …journals-jd.upm.edu.my/Pertanika PAPERS/JST Vol. 26 (3) Jul. 2018... · Validate ML Model and OCL Epressions using SE Tool Pertanika

Pertanika J. Sci. & Technol. 26 (3): 1465 - 1480 (2018)

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ISSN: 0128-7680 © 2018 Universiti Putra Malaysia Press.

ARTICLE INFO

Article history:Received: 20 November 2017Accepted: 28 June 2018

E-mail addresses: [email protected] (Arifa Bhutto)[email protected] (Dil Muhammad Akbar Hussain)*Corresponding Author

Validate UML Model and OCL Expressions Using USE Tool

Arifa Bhutto* and Dil Muhammad Akbar HussainDepartment of Energy and Technology, Aalborg University, Esbjerg, Denmark

ABSTRACT

Verification and validation of system models at design level has a huge impact on the quality of the system software engineering process. In general, system modeling and designing Unified Modelling Language (UML) is a standard for the design models of the systems. However, verification and validation of UML models at early design level is not available, but somehow Object Constraint Language (OCL) constraints are defined at the class level to ensure that the model is correctly designed. As for the static–dynamic structure, there is no such mechanism defined in UML/OCL that has a huge impact on the development of the software. Our research is focused on providing verifiable UML/OCL models. Our approach using UML-based Specification Environment (USE) for UML class model is integrated with the OCL constraints to check if the model is correctly designed as well as constraints for verification and validation. In USE, the output is shown as the verifiable UML/OCL models by visual graphical models.

Keywords: OCL constraints, static and dynamic, Unified Modelling Language (UML) and Object Constraints Language (OCL), verification and validation

INTRODUCTION

Unified Modelling Language (UML) is the co-stander for development of the software engineering system. UML is based on different models which are described at

different levels of abstraction of the system. However, in UML models for verification, various types of languages are integrated to make sure the model is correctly designed and developed; among them Object Constraint Language (OCL) is used for the verification and validation of static and dynamic properties of the design models defined by Richters and Gogolla(2002), for further model-driven approaches discussed by Dang and Gogolla (2009).

However, there are various tools designed for the verification and validation of the UML/OCL, like OCL constraints solver for UML/OCL that defines the Java API for the class

Arifa Bhutto and Dil Muhammad Akbar Hussain

1466 Pertanika J. Sci. & Technol. 26 (3): 1465 - 1480 (2018)

model using java programming for verification of OCL expression and satisfying the model condition defined by Ali, Iqbal, Arcuri and Briand (2011). UML2Alloy, another project started in 2005, is a scientific approach to use two critical functionalities of the Alloy Analyser to simulate and verification of the UML class diagram contained OCL constraints to ensure that the properties of the model are satisfied by Anastasakis, Bordbar, Georg and Ray (2007), and Cabot, Clarisó and Riera (2014).

UMLtoCSP (Cabot, Clarisó, & Riera, 2007) is a tool for automatic verification of UML models with OCL constraints. The model checks correctness for properties of the models. UMLtoCSP tool checks for satisfiability and contradictory constraints. It supports only UML class diagrams and shows a graphical view of the system (Cabot et al., 2007).

The research is focused on the verification of the UML/OCL expressions by USE tool (Gogolla, Büttner, & Richters, 2007). The tool supports the graphical view of the model and also checks the OCL constraints by applying variants and Pre–Post conditions by logical reasoning illustrated by Doan and Gogolla (2018). The following are the steps as illustrated in Figure 1.

Figure 1. UML/OCL verification and validation using USE tool

Step1

The design of the application is described by the structure model in UML class, object

diagram and behavior of the system including the constraints by the OCL. The USE

specification is described in the UML classes, attributes, operations, and association. The

class diagrams integrated with OCL constraints as form of invariants and Pre–Post conditions

(Gogolla et al.,2007).

Step2

Open the USE specification model that generates the graphical view of the class model

including the relationships among the classes.

Step3

Check if the model structure is correct, then USE will verify behavioral properties of the

system model by analyzing the object diagram, which generates the sequence diagram in

connection.

Step4

Figure 1. UML/OCL verification and validation using USE tool

Step 1

The design of the application is described by the structure model in UML class, object diagram and behavior of the system including the constraints by the OCL. The USE specification is described in the UML classes, attributes, operations, and association. The class diagrams integrated with OCL constraints as form of invariants and Pre–Post conditions (Gogolla et al., 2007).

Step 2

Open the USE specification model that generates the graphical view of the class model including the relationships among the classes.

Validate UML Model and OCL Expressions using USE Tool

1467Pertanika J. Sci. & Technol. 26 (3): 1465 - 1480 (2018)

Step 3

Check if the model structure is correct, then USE will verify behavioral properties of the system model by analyzing the object diagram, which generates the sequence diagram in connection.

Step 4

The USE model checks the UML class diagram relations, OCL constraints, invariants, and Pre–Post condition to make sure that all OCL constraints are applied correctly and respond to the violation of the constraints as form of the error detected.

In section II, we will further discuss the aforementioned steps in a detailed case study.

CASE STUDY

This section describes the small application model to check and verify the designed approach by using the UML 2.2 and USE tool. The School Management System (SMS) is a complete framework for the management of the school. The main functions of the application are the following models:

• Student admission module

• Class distribution and timetable module

• Employee management module

• Payroll management module

• Accounts management module

• Generating reports

However, the detailed design of all model components of SMS is shown in Figure 2.

VERIFYING METHODOLOGY

Consider the aforementioned study first; we design the component diagram of the case study using UML in Figure 2 and it represents the SMS requirement models of the case study in detail. The internal structure of the components model is based on the object class structure, therefore we design the class structure of the SMS case study using UML, shown in Figure 3. According to the real requirements, class diagrams represent the entities, data types, functionalities, and relationships of various entities. In UML, class structure shows the data types, operations, and relationships. Using the example of our case study, we developed the models describing employees, departments, accounts, with attributes, operations, and relationships of the classes as shown in Figure 3. Furthermore, we integrated the class diagram with OCL constraints, which we described in the natural language. Using OCL language, these constraints are integrated with the UML class diagrams.



Figure 2. School Management System (SMS) in UML components diagram

Figure 2. School Management System (SMS) in UML

components diagram

Figure 3. UML class diagram of School Management System (SMS) Figure 3. UML class diagram of School Management System (SMS)



Constraints in natural language:

1. The employer must be working in a department.

2. The employer age is not equal to or greater than 20 years.

3. Employer accounts must be active.

4. If employee’s account opening balance is greater than or equal to 5000.


6. Employer must be working in department.

The research methodology is based on selecting the USE tool, which validates the UML class diagram, generating object diagram, sequence diagram from the USE specification. The system also validates the model constraints in the form of OCL, variants, Pre–Post conditions in running the environment automatically.

USE specification of UML class model of SMS Case Study

The USE tool defines the model description in textual format with the extension of use. The UML class diagram is translated into the USE specification that is shown below. Classes, attributes, operations, association, constraints, and Pre–Post conditions in the textual format are listed below:-- Example illustrating Pre-and Post-conditions

Constraints in natural language:

1. The employer must be working in a department.

2. The employer age is not equal to or greater than 20 years.


4. If employee’s account opening balance is greater than or equal to 5000.


6. Employer must be working in department.

The research methodology is based on selecting the USE tool, which validates the UML

class diagram, generating object diagram, sequence diagram from the USE specification. The

system also validates the model constraints in the form of OCL, variants, Pre–Post conditions

in running the environment automatically.

USE specification of UML class model of SMS Case Study

The USE tool defines the model description in textual format with the extension of use. The

UML class diagram is translated into the USE specification that is shown below. Classes,

attributes, operations, association, constraints, and Pre–Post conditions in the textual format

are listed below:

-- Example illustrating Pre-and Post-conditions

model School_Management_System

-- classes

class Employee

attributes

staffid : Integer

staffname : String

fathername : String

address : String

gender : String

contect : Real

age : Integer

salary : Real

designation : String

subject : String

experience : Integer

qualification : String

active : Integer

accountid : Integer

deptid : Integer

operations

raiseSalary(rate : Real) : Real

end

class Accounts

attributes

accountid : Integer

accountname : String

staffid : Integer

bankname : String

openingbalance : Real

accountno : Real

active : Integer

deptid : Integer

operations

hire(e : Employee)

fire(e : Employee)

end

class Department

attributes

deptid : Integer

deptname : String

accountid : Integer

staffid : Integer

operations

add (a : Accounts)

remove (a : Accounts)

end




subject : String



active : Integer

accountid : Integer

deptid : Integer

operations


end

class Accounts

attributes

accountid : Integer


staffid : Integer

bankname : String


accountno : Real

active : Integer

deptid : Integer

operations

hire(e : Employee)

fire(e : Employee)

end

class Department

attributes

deptid : Integer

deptname : String

accountid : Integer

staffid : Integer

operations

add (a : Accounts)


end

-- associations

association WorksIn between

Employee[*]

Department[1..*]

end

association Controls between

Department[*]

Accounts[*]

end

association Having between

Employee[1]

Accounts[*]

end

-- constraints

constraints

context Employee inv:

age >= 20

context Department inv:

staffid = 1

context Accounts inv:

accountid=active


openingbalance >= 5000


staffid = deptid


staffid= accountid

context Employee::raiseSalary(rate : Real) : Real

post raiseSalaryPost:


subject : String



active : Integer

accountid : Integer

deptid : Integer

operations


end

class Accounts

attributes

accountid : Integer


staffid : Integer

bankname : String


accountno : Real

active : Integer

deptid : Integer

operations

hire(e : Employee)

fire(e : Employee)

end

class Department

attributes

deptid : Integer

deptname : String

accountid : Integer

staffid : Integer

operations

add (a : Accounts)


end



-- associations


Employee[*]

Department[1..*]

end


Department[*]

Accounts[*]

end


Employee[1]

Accounts[*]

end

-- constraints

constraints


age >= 20


staffid = 1


accountid=active




staffid = deptid


staffid= accountid



salary = salary@pre * (1.0 + rate)

post resultPost:

result = salary

context Accounts::hire(e : Employee)

pre hirePre1: e.isDefined()

pre hirePre2: employee->excludes(e)

post hirePost: employee->includes(e)

context Accounts::fire(e : Employee)

pre firePre: employee->includes(e)

post firePost: employee->excludes(e)

After writing the aforementioned specifications in textual form, USE model opens the

specifications shown in Figure 3. GUI environment is shown graphically in class diagram,

association, OCL constraints, variants, and Pre–Post conditions.

Using GUI environment, models are viewed and the errors are found by messages, structure

is correct or not as well as define number of classes, association, invariants, Pre–Post

conditions as shown in Figure 3. In the next section, we validate the model using the OCL

constraints by applying the object data and runtime we check the results of the UML object,

class models

After writing the aforementioned specifications in textual form, USE model opens the specifications shown in Figure 3. GUI environment is shown graphically in class diagram, association, OCL constraints, variants, and Pre–Post conditions.

Using GUI environment, models are viewed and the errors are found by messages, structure is correct or not as well as define number of classes, association, invariants, Pre–Post conditions as shown in Figure 4. In the next section, we validate the model using the OCL constraints by applying the object data and runtime we check the results of the UML object, class models

-- associations


Employee[*]

Department[1..*]

end


Department[*]

Accounts[*]

end


Employee[1]

Accounts[*]

end

-- constraints

constraints


age >= 20


staffid = 1


accountid=active




staffid = deptid


staffid= accountid





CREATE OBJECT AND VALIDATE THE DATA

In the USE tool, we can create the object by selecting the option create object shown in Figure 5. We can also directly set the data in the object model by using the option add data as shown in Figure 6 in USE model, we can set the data by command prompt as shown in the listing below:

Figure 3. USE tool generating class diagram and association


In the USE tool, we can create the object by selecting the option create object shown in

Figure 4. We can also directly set the data in the object model by using the option add data as

shown in Figure 5 in USE model, we can set the data by command prompt as shown in the

listing below: use> !create Accounts : Department

use> !create mehran : Employee

use> !set mehran.staffname :='Ali'

use> !set mehran.salary :=1500000



use> !set mehran.age :=24




In the USE tool, we can create the object by selecting the option create object shown in

Figure 4. We can also directly set the data in the object model by using the option add data as

shown in Figure 5 in USE model, we can set the data by command prompt as shown in the

listing below: use> !create Accounts : Department







Figure 4. Object diagram of SMS in USE tool

Figure 5. Class, object diagram with data, and properties of the objects




DEFINE MODEL INHERITANCE CONSTRAINTS

Model also checks the constraints by the form of invariants if the constraints are violating the system by giving the message: Model inherent constraints violated. In the USE, invariants messages show that there is a problem in the state; we can view the message of the invariants violation in the GUI panel shown at the bottom of the screen. The command prompt also has check command to view the violated comments as shown in the listing below


Figure 5. Class, object diagram with data, and properties of the objects Figure 6. Class, object diagram with data, and properties of the objects


Model also checks the constraints by the form of invariants if the constraints are violating the

system by giving the message: Model inherent constraints violated. In the USE, invariants

messages show that there is a problem in the state; we can view the message of the invariants

violation in the GUI panel shown at the bottom of the screen. The command prompt also has

check command to view the violated comments as shown in the listing below use> check

Multiplicity constraint violation in association

`WorksIn´

Object Àccounts´ is connected to 0 object(s) of class

`Department´

but the multiplicity is specified as `1. *'


`WorksIn´

Object `Mehran´ is connected to 0 object(s) of class

`Department´

but the multiplicity is specified as `1.. *'

According to the above class diagram in UML, it is specified that each employee works in the

department. USE GUI model shows the object diagram; there is no employee who works in

the department in association link. We can fix this in GUI model as well as by command

prompt by just typing the insert command for inserting the missing association listed below:

use>!insert (mehran, Accounts) into worksIn

The USE GUI environment connected the link directly by inserting the object using the

object diagram option or inserting the command directly from the command prompt.

The USE diagram, Figure 6, shows the red link in the object diagram between department

and employee object, which is the violation of invariants; we can fix it by applying the

correct rules for invariants, which is shown in Figure 7 of the model diagrams using USE

GUI.



According to the above class diagram in UML, it is specified that each employee works in the department. USE GUI model shows the object diagram; there is no employee who works in the department in association link. We can fix this in GUI model as well as by command prompt by just typing the insert command for inserting the missing association listed below:


Model also checks the constraints by the form of invariants if the constraints are violating the

system by giving the message: Model inherent constraints violated. In the USE, invariants

messages show that there is a problem in the state; we can view the message of the invariants

violation in the GUI panel shown at the bottom of the screen. The command prompt also has

check command to view the violated comments as shown in the listing below use> check


`WorksIn´

Object Àccounts´ is connected to 0 object(s) of class

`Department´

but the multiplicity is specified as `1. *'


`WorksIn´

Object `Mehran´ is connected to 0 object(s) of class

`Department´

but the multiplicity is specified as `1.. *'

According to the above class diagram in UML, it is specified that each employee works in the

department. USE GUI model shows the object diagram; there is no employee who works in

the department in association link. We can fix this in GUI model as well as by command

prompt by just typing the insert command for inserting the missing association listed below:

use>!insert (mehran, Accounts) into worksIn

The USE GUI environment connected the link directly by inserting the object using the

object diagram option or inserting the command directly from the command prompt.

The USE diagram, Figure 6, shows the red link in the object diagram between department

and employee object, which is the violation of invariants; we can fix it by applying the

correct rules for invariants, which is shown in Figure 7 of the model diagrams using USE

GUI.

The USE GUI environment connected the link directly by inserting the object using the object diagram option or inserting the command directly from the command prompt.

The USE diagram, Figure 7, shows the red link in the object diagram between department and employee object, which is the violation of invariants; we can fix it by applying the correct rules for invariants, which is shown in Figure 8 of the model diagrams using USE GUI.

METHOD FOR CHECKING INVARIANTS

Checking class invariants automatically, the USE graphical interface has a capability to view the changes directly. We can change the status and the GUI shows the results. OCL invariants can be analyzed by applying the commands listed below:


Checking class invariants automatically, the USE graphical interface has a capability to view

the changes directly. We can change the status and the GUI shows the results. OCL invariants

can be analyzed by applying the commands listed below: Department::hire(self:Accounts, e:mehran) [caller:

openter Accounts hire(mehran)@<input>:1:0]

use> info vars

[frame 1]

e : Employee = mehran

self : Department = Accounts

[frame 0]

empty

[object variables]

Accounts : Department = Accounts

mehran : Employee = mehran

use> !insert (e,Accounts) into WorksIn

use> !openter mehran raiseSalary(0.1)

use> !set self.salary := self.salary+ self.salary * rate

use> !create Accounts : Department




use> !openter Accounts hire(mehran)

precondition `hirePre1' is true


use> info opstack

1. Department::hire(self:Accounts, e:mehran) [caller:


use> info vars

[frame 1]



[frame 0]




Checking class invariants automatically, the USE graphical interface has a capability to view

the changes directly. We can change the status and the GUI shows the results. OCL invariants

can be analyzed by applying the commands listed below: Department::hire(self:Accounts, e:mehran) [caller:


use> info vars

[frame 1]



[frame 0]

empty

[object variables]





use> !set self.salary := self.salary+ self.salary * rate

use> !create Accounts : Department




use> !openter Accounts hire(mehran)



use> info opstack

1. Department::hire(self:Accounts, e:mehran) [caller:


use> info vars

[frame 1]



[frame 0]

empty

[object variables]




use> !set e.salary :=2000

use> !opexit

postcondition `hirePost' is true

use> info opstack

no active operations.

use> info vars

[frame 0]

empty

[object variables]



use> !openter mehran raseSalary(0.1)

<input>:1:0: No operation `raseSalary'found in class

Èmployee'.


use> !set self.salary := self.salary + self.salary *

rate

use> !opexit 2200

postcondition `raisesalarypost' is true

postcondition `resultpost' is true

DISCUSSION

The results of the design model shown by the USE GUI generate the sequence diagram to

visualize the variants, Pre–Post conditions by directly applying an object to validate the

model according to the data. In Figures 8 and 9, communication model represents the object

data including the actual data and relationships of the objects. Figure 10 shows the object,

class variants, and counts how many objects are defined as well as class invariants checked-

the invariants view of the class by green check that all invariants are correct. Figure 11 shows



DISCUSSION

The results of the design model shown by the USE GUI generate the sequence diagram to visualize the variants, Pre–Post conditions by directly applying an object to validate the model according to the data. In Figures 9 and 10, communication model represents the object data including the actual data and relationships of the objects. Figure 11 shows the object, class variants, and counts how many objects are defined as well as class invariants checked- the invariants view of the class by green check that all invariants are correct. Figure 12 shows the complete model behavior and all sub-models like state shows the model status, communication, object, class, class invariants, and sequence. The model output shows that the verification and validation process of the school management system design is done correctly by UML/OCL constraints applied on object class models.

Figure 6. Invariants not satisfied shows in object Link diagram by red line

Figure 7. Sequence diagram represent invariants

Figure 7. Invariants not satisfied shows in object Link diagram by red lineFigure 6. Invariants not satisfied shows in object Link diagram by red line

Figure 7. Sequence diagram represent invariants Figure 8. Sequence diagram represent invariants



Figure 8. Sequence diagram represents invariants correct

Figure 9. Sequence diagram represents invariants correct

Figure 10. Object, class variants, and counts of the object including sequence diagram( Overall USE Environment )

Figure 9. Communication diagram


The model shows the red line in Figure 6 when we write the wrong invariants. Figure 7 shows the invariants violation in sequence diagram, which indicates that the model does not provide the right invariants to validate the model.



Figure 10. Object, class variants, and counts of the object including sequence diagram( Overall USE Environment )


Figure 11. Object, class variants, and counts of the object including sequence diagram (Overall USE Environment )

Figure 11. Complete vview of the USE model overview

Figure 12. Complete vview of the USE model overview



CONCLUSION

This paper is an approach for verification and validation of structural and behavioral properties of UML model integrated with the OCL constraints. The input we select is USE application that describes the class structure and applies the OCL constraints as a form of invariants. As an output, we found the verifiable UML class, object, and sequence model. We apply this methodology on the small case, which shows very impressive results for the verification and validation of UML models.

Our future work will continue in different directions, like all the models are generated automatically and adding the frame conditions to UML and OCL models.

ACKNOWLEDGEMENT

This research work was conducted and supported by the Department of Energy and Technology, Aalborg University, Denmark. Authors greatly acknowledge and appreciate their excellent unconditional support for using laboratories and other facilities. Special thanks to Jens Bo, Head of the Section at Esbjerg Campus for his constant involvement in keeping the status updated with short seminar/presentations.

REFERENCESAli, S., Iqbal, M. Z., Arcuri, A., & Briand, L. (2011, July). A search-based OCL constraint solver for

model-based test data generation. In 11th International Conference on Quality Software (QSIC), 2011 (pp. 41–50). IEEE.

Anastasakis, K., Bordbar, B., Georg, G., & Ray, I. (2007, September). UML2Alloy: A challenging model transformation. In International Conference on Model Driven Engineering Languages and Systems (pp. 436–450). Springer, Berlin, Heidelberg.

Cabot, J., Clarisó, R., & Riera, D. (2007, November). UMLtoCSP: A tool for the formal verification of UML/OCL models using constraint programming. In Proceedings of the Twenty-Second IEEE/ACM International Conference on Automated Software Engineering (pp. 547–548). ACM.

Cabot, J., Clarisó, R., & Riera, D. (2014). On the verification of UML/OCL class diagrams using constraint programming. Journal of Systems and Software, 93, 1–23.

Dang, D., & Gogolla M., (2009). Precise model-driven transformations based on graphs and met models. In 7th IEEE International Conference on Software Engineering and Formal Methods (pp. 23–27). IEEE.

Doan, K. H., & Gogolla, M. (2018). Logical reasoning with object diagrams in a UML and OCL tool. In P. Chapman, A. Moktefi, & G. Stapleton, (Eds.), Proceedings of the 10th International Conference on Diagrams (DIAGRAMS 2018). Springer, LNCS, Berlin, Heidelberg.

Gogolla, M., Büttner, F., & Richters, M. (2007). USE: A UML-based specification environment for validating UML and OCL. Science of Computer Programming, 69(1–3), 27–34.

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Documents

Validate UML Model and OCL Expressions Using USE …journals-jd.upm.edu.my/Pertanika PAPERS/JST Vol. 26 (3) Jul. 2018... · Validate ML Model and OCL Epressions using SE Tool Pertanika